It is typically thought that the discrimination of gaze direction relies on
the use of the ratio of iris to sclera in the visible part of the eye.
However, when people move their eyes, their change in eye direction also
carries a motion signal. Here, we directly compared the relative contribution
of motion vs. geometrical cues in the perception of another's gaze.
Participants were shown two images: a person looking straight ahead and then
looking to the left or right 3 different distances from centre. This resulted
in the apparent motion of the eyes to the left or right. To eliminate the
motion signal, participants received the final eye position only. Geometrical
cues were manipulated with contrast polarity. Participants judged the
direction of the perceived eye movement. Results suggest that both motion
cues and geometrical cues systematically influence the perception of gaze.